Pressure Ulcer Detection Methods, Devices and Techniques

ABSTRACT

A system for determining the location of patients uses a patient-associated communicator which wirelessly communicates with a network of environmental reference communicators arranged at fixed or otherwise known locations. A camera can be used to monitor or detect pressure ulcers and relay the information to a host system. Other embodiments are also disclosed.

RELATED APPLICATIONS

This application is related to and claims the benefit under 35 USC 371of PCT/US2014/59756, filed Oct. 8, 2014, which in turn claims thebenefit of U.S. provisional patent application Ser. No. 61/888,078,filed Oct. 8, 2013, Ser. No. 61/905,106, filed Nov. 15, 2013, and Ser.No. 62/047,642, filed Sep. 8, 2014. This application is further relatedto and claims the benefit as a continuation-in-part of co-pending U.S.patent application Ser. No. 13/070,189, filed Jun. 6, 2011, and throughit the benefit of U.S. provisional patent application Ser. No.61/438,732, filed Feb. 2, 2011, entitled System for Optimizing PatientTurning, Ser. No. 61/326,664, filed Apr. 22, 2010, entitled Methods andDevices that Enable the Sensing of Body Surface Markers for thePrevention and Treatment of Pressure Ulcers and Other Wounds, Ser. No.61/411,647, filed Nov. 9, 2010, entitled Method and Device for SurfacePressure Monitoring, Ser. No. 61/393,364, filed Oct. 15, 2010, entitledPatient Position, Orientation, and Surface Pressure Monitoring Device,and Ser. No. 61/373,260, filed Aug. 12, 2010, entitled Sensing Systemthat Automatically Identifies and Tracks Body Surface Markers to Allowfor the Delivery of Targeted Therapy. This application is also relatedto and claims the benefit as a continuation-in-part of co-pending U.S.patent application Ser. No. 14/244,720, which is a 35 USC 371application claiming the benefit of PCT/US2012/000488, priority dateOct. 3, 2012, and in turn claims the benefit of U.S. provisionalapplication Ser. No. 61/542,785, filed Oct. 3, 2011. Finally, thisapplication is a continuation-in-part of U.S. patent application Ser.No. 14/543,887, filed Nov. 17, 2014, which in turn claims the benefit ofU.S. provisional patent application Ser. No. 61/905,105, filed Nov. 15,2013, and Ser. No. 62/047,642, filed Sep. 8, 2014. The presentapplication claims the benefit of each of the foregoing, all of whichare incorporated herein by reference.

FIELD OF THE INVENTION

Aspects of the present invention relate generally to systems, devicesand methods for the detection of compromised tissue perfusion and otherissues affecting the health of a patient, and more particularly relatesto systems, devices and methods for such detection, communicating ofrelevant information to a host, and providing either appropriateguidance to a caregiver to facilitate proper management of the patientor device instructions for providing automated care.

BACKGROUND OF THE INVENTION

Management of pressure ulcers and other health conditions poses asubstantial burden to the healthcare system. Each year, the UnitedStates spends billions of dollars treating pressure ulcers andassociated complications. Pressure ulcers are very common and theyrepresent a significant source of morbidity and mortality for patients.The prevalence of pressure ulcers in the US alone is estimated to bebetween 1.5 and 3.0 million people, with two thirds of cases involvingpatients 70 or older.

Pressure ulcers, which are also known as pressure sores, bed sores, ordecubitus ulcers, represent localized areas of tissue damage. Pressureulcers often occur when the soft tissue between a bony prominence and anexternal surface is compressed for an extended period of time. Pressureulcers can also occur from friction, such as by rubbing against a bed,cast, brace, or the like. Pressure ulcers commonly occur in immobilizedpatients who are confined to a bed, chair or wheelchair. Localizedtissue ulceration results when pressure on the skin exceeds capillaryfilling pressure (approximately 32 mm Hg), which thereby impedes themicro-circulation in the skin and the underlying subcutaneous tissue.With compromised blood flow, the delivery of oxygen and nutrients totarget tissues is impaired. If blood flow is not restored promptly, theskin and subcutaneous tissue will die and a pressure ulcer will develop.

Pressure ulcers will initially appear as areas of red or pink skindiscoloration, but these areas can quickly develop into open wounds ifleft untreated. Open wounds can lead to severe health complications byexposing patients to life-threatening infections. The primary goal inthe treatment and prevention of pressure ulcers is to relieve pressureon and around affected tissues. Pressure relief can be accomplished byfrequently changing the position of immobilized patients and by usingsupport surfaces that minimize surface pressure. Although pressuremanagement is the most critical aspect of any successful treatmentprogram, it is also important to ensure that patients receive adequatenutrition, engage in daily exercise, and follow a good skin care andpersonal hygiene protocol.

Various devices and methods for treating and preventing pressure ulcershave been developed. The cornerstone of pressure ulcer prevention is toturn patients on a regular basis, such as every one or two hours.Patients confined to a wheelchair, chair, or other surface should bemoved in such a manner. Intermittent relief of surface pressure hasproven to be highly effective in preventing the development of pressureulcers. However, various factors limit compliance withturning/repositioning protocols.

There is a long-felt, definite and even urgent need for a system,method, and device that helps to prevent, detect, and/or treatpressure-induced ischemia and pressure ulcers by optimizing surfacepressure at areas of compromised tissue perfusion. Various aspects ofthe present invention accomplish these objectives and substantiallydepart from the conventional concepts and designs of the prior art.

SUMMARY OF THE INVENTION

The present invention provides, in various aspects, a more accuratemeans for determining the location of patients with respect to a careenvironment. In an embodiment, a patient-associated communicator (“PAC”)is capable of sending and/or receiving wireless signals and determiningits orientation relative to a patient and/or the environment. Aplurality of environmental reference communicators (ERCs) aredistributed at fixed or known reference locations. The PACs communicatewith one or more ERCs, permitting a specific PAC location to bedetermined. In various embodiments, the PACs can be affixed to thepatient, or can be a beacon or other device affixed to a patient bed. Insome embodiments the PACs have indicia so that a user such as acaregiver can easily orient the sensor with respect to the patient.

In another aspect, a camera in communication with either the PACs or theERCs is used to visually document the presence, absence, currentcondition, or progression of pressure ulcers for a monitored patient.That data is logged and stored for appropriate analysis. Imagestandardization can be provided to permit visual data obtained from acamera to be standardized to, for example, improve documentation. Imagecharacteristics that may need to be standardized include imageorientation, viewing angle, viewing distance, brightness, color, etc. Toassist in image standardization, a visual reference may be placed withinthe field of the image.

To assist in monitoring patient position, PACs can, in some embodiments,include indicators such as LEDs that can indicate which side the patientis on, when a patient requires a turn, which area of the body has beenexposed to the most pressure, which direction a patient should be turnedonto, or when a patient has been turned sufficiently to satisfy aturning protocol or to depressurize a given area.

In another aspect of the invention, patient self-roll or repositioningcan be encouraged by various means, such as audio, visual orphysical/tactile guidance. In a related aspect, acceleration andorientation monitoring of the patient may be used to monitor for motioncaused by an alternating pressure mattress. The monitoring system of thepresent invention, by detecting patient accelerations, can determine ifa patient is being repositioned sufficiently. In some embodiments, thesystem can include a pressure measurement system which can produce apressure map of reasonable precision that then feeds back to a supportsurface.

In yet another aspect, patients who are immobilized for long periods oftime often require prophylaxis to prevent against deep venous thrombosis(DVT). Patients considered at risk for DVTs will generally receive DVTprophylaxis, which can be pharmacologic or mechanical in nature.

In another aspect, the system can automatically calculate at least onesuggested decompression threshold/interval. The decompressionthreshold/interval refers to the minimum amount of time that an area ofthe body needs to experience reduced pressure or no pressure in order toadequately re-profuse that area of the body, thereby preventing ischemiaand tissue damage. In a further related aspect, the present inventioncan also detect system can also detect very low to no movement orsituations in a patient, such as when the patient's breathing,heartbeat, and other physical motions have stopped.

In a still further related aspect, a badge, nametag, bracelet, or otherwearable device which is recognized by the system of the presentinvention can be worn or carried by the caregiver. The caregiver isassociated with one or more wearable devices, which each comprises anidentifier (such as a name, number, code, etc.). The wearable devicewirelessly transmits to base stations that are in known locations. Inanother aspect, the caregiver can communicate with the PAC by physicalinteraction, such as by tapping on the PAC to indicate a completed turnor other event.

These and other aspects of the invention can be better appreciated fromthe following Figures.

THE FIGURES

FIG. 1 illustrates a first aspect of the invention, in which a sensorassociated with a patient communicates with a camera generating visualdata concerning the condition of a patient, which data is associatedwith the patient in the caregiver's data processing system.

FIG. 2 illustrates a second aspect of the invention, in which a sensorassociated with a known reference point cooperates with a camera to linkvisual data relating to a patient's condition to the patient in thecaregiver's data processing system.

FIG. 3 illustrates a third aspect of the invention, in which multipletransmitters in known locations within a room communicate with a cameraand a communicator affixed to the patient.

FIG. 4 illustrates a technique for assisting in image standardizationand image capture.

FIG. 5 illustrates an alternative technique for assisting in imagestandardization and image capture.

FIG. 6 illustrates a technique for visually comparing the current andprior status of an area of interest.

FIGS. 7A-7B illustrate an embodiment in which indicators such as LEDsare provided on the sensor so as to be visible through the housing ofthe sensor, for assisting in indicating patient position.

FIGS. 8A-8B illustrate an embodiment of the invention in which thepatient is encouraged to self-roll.

FIG. 9 illustrates an embodiment in which identification of thecaregiver is implemented.

FIG. 10 illustrates an embodiment of the invention in which deep veinthrombosis risk can be monitored.

DETAILED DESCRIPTION OF THE INVENTION Location Sensing—Orientation-BasedLocation Analysis

In an aspect of the present invention a more accurate means fordetermining the location of patients with respect to a care environmentis provided. A wireless communicator is associated with a patient,referred to herein as a patient-associated communicator (PAC). The PACcomprises an antenna that is capable of sending or receiving wirelesssignals. The PAC also has a means for determining its orientation(including the orientation of the PAC's antenna) relative to a patientand/or the environment. Such means for determining the PAC's orientationinclude an accelerometer, gyroscope, or magnetometer. In someimplementations, the PAC has a directional antenna. The PAC can bephysically attached to a patient, or can be in close proximity to apatient, or can be in a known location/position/orientation relative toa patient. The PAC can communicate with other PACs and can alsocommunicate with external wireless communicators that are located atfixed/known reference locations within the patient care environment.Communicators that are located at fixed/known reference locations withina patient care environment will be referred to herein as environmentalreference communicators (ERCs).

There are various ways that the location of a PAC (and hence thelocation of the corresponding patient) can be determined. A PAC cancommunicate with one or more ERCs, and since the location of ERCs isknown, the location of PACs can therefore be determined by analyzing therelationship of a PAC to the various ERCs. Since the approximatetransmitting range of PACs and ERCs is known, an approximate locationfor a PAC can be determined simply by knowing which ERCs a PAC iscommunicating with. If a PAC is communicating with an ERC, then the PAC(and therefore the corresponding patient) must reside within the samegeneral location as the ERC (defined by the transmitting range of thePAC/ERC). Patient location can be determined more accurately byanalyzing time of flight, perceived signal strength, or viatriangulation of a PAC relative to multiple ERCs. These methods are wellknown to those familiar in the art.

Disclosed herein is a novel method and device for improved patientlocation tracking. In one implementation of the present invention, thepatient-associated communicator is physically attached to a patient,such as on the patient's anterior chest. Given that the human bodyattenuates wireless signals, a wireless communicator that is placed onthe patient's anterior chest may transmit more effectively in ananterior direction, and less effectively in a posterior direction (sincethe signal may be attenuated by the body tissue). As a result, theantenna of the patient-associated communicator can be configured to bedirectional. Since the human body can have a variety of differentshapes, sizes, tissue densities, etc. the amount of signal attenuationcan vary from person to person. To further accentuate the directionalityof the antenna and provide a more consistent transmission profile acrosssubjects, in some embodiments a radio-opaque backing can be applied toone or more sides of the communicator, such that wireless transmissionoccurs preferentially in one direction.

As the patient-associated communicator changes location/orientationwithin a care environment, it will become more or less visible todifferent environmental reference communicators. Given that the PAC hasdirectionality, when the PAC rotates along a single axis in a fixedlocation, it will become more or less visible to different ERCs. Forexample, consider a patient care environment that has a single PAC and asingle ERC. When the PAC is oriented directly towards the ERC, the ERCcan detect the presence of the PAC. Using the perceived signal strength,or time of flight, the location of the patient can be more accuratelydetermined. However, as the patient begins to rotate along an axis butremains in a fixed location (i.e. the PAC changes its orientationrelative to the ERC), the perceived signal strength and/or time offlight will change. This example illustrates how changes in not only thelocation, but also the orientation of a directional PAC relative to anERC will change the perceived signal strength. Therefore, the locationof a directional PAC can be more accurately determined if theorientation of the PAC is known.

FIG. 1A illustrates how a PAC applied to the anterior chest can have asubstantially directional transmission profile. The transmitted signalis attenuated by body tissues, radiopaque coatings, or other means, andhence signal strength varies with direction relative to a receiver.

In the example of FIG. 1B, although the directional PAC is equidistantfrom each ERC, the perceived signal strength varies based on theorientation of the PAC relative to each ERC. In the example above, theperceived signal strength between ERCs #1 and 4 and the PAC isrelatively low, and thus the calculated distance between ERCs 1 and 4and the PAC may be determined to be large. There is no signaltransmission between ERC #3 and the PAC. However, the perceived signalstrength between ERC #2 and the PAC is high, and thus the calculateddistance may be determined to be small. Although the actual distancesbetween each ERC and the PAC is the same, the calculated distances varybased on the orientation of the PAC relative to each ERC.

In FIG. 10, the perceived signal strength profiles between the PAC andthe four ERCs is the same, although the PAC is in different locations(Location A vs. Location B). The signal strength profiles are the same,despite the different locations, because the orientation of the PACrelative to the ERCs has changed. This example illustrates how thelocation of a directional PAC cannot be accurately determined based onperceived signal strength alone.

In an aspect of an embodiment of the invention, a novel method forimproving the accuracy of location tracking of a directional PAC byproviding information regarding the orientation of the directional PACrelative to ERCs. As mentioned previously, the PAC has a means fordetermining the orientation of its antenna relative to the patientand/or the environment. The orientation of the PAC's antenna can bedetermined using sensors such an accelerometer, gyroscopic sensor,and/or magnetometer. The PAC will communicate its spatial orientationrelative to an ERC. With knowledge of the orientation of the PACrelative to the patient, the perceived signal strength can be moreaccurately analyzed to help determine the location of a PAC relative toERCs.

In order to know how the orientation of a given PAC affects thecommunication to an ERC in terms of perceived signal strength, time offlight, etc, a system calibration step can be performed. When the systemis initially installed and the environmental reference communicators areplaced in relatively known locations, a calibration step can becompleted to determine the communication readings (signal strength, timeof flight, etc) from a PAC at a given location for all possible PACorientations, or a subset of common orientations. This calibration stepcan be done with a calibrating unit that simulates the patient (at leastin terms of RF or wireless transmission) and rotates through variousdifferent orientations.

This calibration can be done for bed locations such that bed assignmentsto patients are automatically made. The calibration can also be done forother location of chairs, rooms, lounges, bathrooms to help determinelocation of a patient. If more than one location is possible after thelocation analysis, the user may be given a set of possible locations tochoose from. This helps by narrowing down the choices to allow forsimpler interaction with the system. The data of user entries andpatient orientation analysis can be used for the system to learn overtime to improve its location analysis. It can also be used fordetecting, alert, or learning from new obstructions, such as furniture,etc over time. The same orientation based location analysis can be usedwith time of flight or other location analysis as well. The sameorientation based location analysis can be used for objects such asequipment as well.

It should be noted that the location of any object (including patients)can be determined more accurately using the method and device describedherein. For example, equipment can be tagged with a communicator. Theequipment will attenuate the signal in certain directions. Therefore, ifthe orientation of the communicator is known, the system can factor thisinformation into the location mapping system to more accuratelydetermine the location of the equipment.

Since PACs can communicate with each other, if the location of one PACis determined, then, for at least some embodiments, the system can allowPACs to functionally serve as an ERC for other PACs. In this way lessERCs may be used or the location determination may be more robust oraccurate with more effective ERCs.

Once an initial calibration step is done, a user is presented withlocation information of the PAC. The system may have analyzed thelocation of the PAC incorrectly. A user can then enter the correctinformation. This corrected information can be used as data to helpfurther train the system. Additional calibration steps can also be used.In an alternative approach, the system can act with no initialcalibration, and a user enters the initial location and/or orientationinformation. The system uses one or more user inputs to train the systemon the location and orientation information. If the system detects smallchanges in the communication signal information (signal strength, etc)between the PAC and ERCs and the location information is still correct,the system can also use that data to train the system as to the range ofacceptable signal information for a given location. The system can knowthe location information is correct, by getting confirming input fromthe user, by getting no corrections from the user, or by receivingposition information that is consistent with expected data, etc.

Location Sensing—Bed Beacon

Another variant is to have a wireless communicator associated with eachpatient location. For example, a communicator may be placed relative toeach patient bed. The sufficiently close proximity between the patientsensor and the bed beacon/communicator will allow for automaticassociation between a patient and a bed. Proximity sensing can be donewith various methods including signal strength or time or flight. Thecommunication strength of the beacon or sensor can be small as well toprevent ambiguity of assignment, where a patient can be associated withmore than one bed or a bed can be associated with more than one patient.If there is ambiguity, the assignment can be narrowed down to a fewpatients or beds to simplify the association process. The bed beacon canbe plugged in or battery powered. It can be placed on the bed or thewall, as shown at 100 in FIG. 8B. In some embodiments, the beacon canalso display information visually or audibly.

Pressure Ulcer Documentation Using Visual Data Lopping

In an aspect of the invention, an embodiment in accordance with thepresent invention provides an improved method for photographic orvideographic documentation of certain patient conditions, including skinlesions such as pressure ulcers.

In one exemplary instance of this aspect of the invention, shown in FIG.1D, a camera 150 is used to visually document the presence of a pressureulcer and this visual data is then automatically logged and associatedwith a specific patient. In such a fashion, users are provided with animproved method for documenting the presence, absence, current conditionof, or progression of one or more pressure ulcers for a particularpatient. Visual data is captured at the bedside where it isautomatically associated with a specific patient and then stored.

As described in greater detail hereinafter, the camera of the presentinvention automatically associates the recorded visual data with aspecific patient. In one implementation, this association isaccomplished, in part, by utilizing a camera 150 (FIG. 1D) that canwirelessly transmit, receive, or transmit and receive data. The cameracan utilize any number of wireless communication protocols, such asWifi, RFID, Zigbee, 802.15.4, infrared communication, Bluetooth, or anyother communications protocol known to those skilled in the art or laterdeveloped as shown at 160 in FIG. 1D.

As one example, the camera communicates with wireless communicationunits that are associated with specific patients, referred tohereinafter as patient-associated communicators (PACs), shown as 100 inFIG. 1D. The communicator can be associated with a patient identifier,such as the medical record number (MRN or MR#), electronic medicalrecord (EMR), date of birth, social security number, patient name,demographic information, diagnosis, treatment team, location (includingroom number, unit number, etc.), or any other patient data or othersufficiently unique identifier. The communicator 100 can be in closeproximity to the patient, worn by the patient, attached to the patient,in a location associated with the patient such as a room or bed, or infixed/known locations relative to the patient. The PACs can be linked toa specific patient with one or more of the following: The camera cancommunicate with PACs located within transmitting range of the camera,for those implementations where the camera utilizes wirelesscommunications. Data from the PACs (i.e. patient name, MRN, etc.) iscommunicated either wirelessly or wired as shown at 165 in FIG. 1D, andcan be stored in the caregiver's data processing system, shown at 170,along with any visual data subsequently obtained by the camera. If thereare multiple PACs within communicating range of the camera, the cameracan determine which PACs reside in closest proximity to the camera byanalyzing perceived signal strength, time of flight, or other modalitiesknown to those familiar with the art. In such an arrangement, the PACsenable an image to be automatically associated with a patient. Thisreduces the need for users to enter patient information manually andhelps with workflow. The relative or absolute distance between thecamera and PACs can also be determined. The communicating range of thecamera and/or PACs can be modified such that more or fewer PACs becomevisible to the camera. In some implementations, the communicating rangeof the camera and/or PACs can be limited such that only a single PACbecomes visible to the camera. The camera may display a list of allpossible PACs within communicating range of the camera or of the PACsthat are closest to the camera. By displaying the nearby PACs, which mayindicate that there are multiple patients that the system couldautomatically link an image to, the user can select the propercombination of image and medical record. This avoids mistaken linkingwhile at the same time substantially reducing the need to enter data,again improving workflow. The user may then select the PAC that is to bethe focus of visual data collection. Any subsequent visual datacollected by the camera (pictures, videos) is then automatically linkedwith data obtained from the selected PAC (i.e. patient name, MRN, etc.),and the linked data is sent to a central server for logging.

Similarly, as shown in FIG. 2, the camera 200 may include atransmitter/transceiver that sends signals 215 to an environmentalreference communication device or ERC 210 associated with a patient orthe patient's room, to identify with whom any given visual data shouldbe associated. Similar methods as noted above allow for the subject tobe identified specifically when more than one ERC can be communicatedwith. Similarly the camera location, either absolute or relative, can beidentified and the determined location of the camera can be associatedwith the known location of a subject. The location can be identified byproximity to other known entities or locations. Alternatively, thelocation can be determined via means such as signal strength or time offlight analysis to other transmitters/transceivers, including nodes,patient sensors 100, or GPS. Other sensors can be available on thecamera including temperature, humidity, light sensors, audiosensors/microphones, orientation sensors, etc.

In various embodiments of the invention, there are several ways in whicha patient's name and/or demographic information can be automaticallyassociated with images taken of the patient in real-time. One way thisis accomplished is by having a wireless sensor associated with aspecific patient. The sensor has a unique ID, which is then assigned toa patient. This assignment process can either be manual (i.e. manuallyassigning sensor ID to patient's MRN # in computer system) or automatic(i.e. barcode reader scans patient sensor and then patient ID bracelet).There are many ways of assigning the patient sensor to a specificpatient, which are well known to those familiar with the art. The camera(or multimedia device) has a built-in wireless transceiver that candetect any patient sensors within its general proximity. The sensor ID(and/or the name associated with said sensor) is then automaticallydisplayed on the camera. The user then selects the correct sensor ID (orpatient name), and any pictures or images subsequently obtained areassociated with the sensor/patient, until a new sensor/patient isselected.

FIG. 3 illustrates a further aspect of the invention, in which aplurality of transmitters 305 are positioned in fixed or knownlocations, and one or more sensors 300, each associated with a differentpatient, move within space observable by the camera 310. The cameralocation can be determined by triangulation with multiple base stations,and the accuracy of the camera location is improved by knowing theorientation of the transceiver on camera. In such an embodiment, patientlocation can be determined by triangulation with multiple base stations,again with accuracy improved by knowing the orientation of thetransceiver, or communicator, on the associated patient. Because thecamera is linked to the patient sensor, the camera and the sensorcombination associates the visual data with the correct patent.

The camera can upload the data it captures wirelessly to the system,such as via Bluetooth, Wifi, Zigbee or another established or customwireless transfer protocol. The wireless transfer can be accomplished toa computer or computing station at the nursing station or other centrallocation or it can be accomplished through an existing wireless network,such as the patient sensor network, Wifi, or communication node network.The data can also be transferred in a wired fashion, such as by USB,firewire, Ethernet, etc. Alternatively, the data can be transferred byother means such as by USB stick, memory card.

The location of the image taken of skin or a pressure ulcer can beidentified by the user. This can be accomplished by a list of locationsor parameters to help define location, free text entry, or 2D or 3Dimage-based selection, where the user can, for instance, point to ordrag and drop a location on a visual representation of the patient. Asimilar 2D or 3D representation can be used to identify areas that areat risk, have existing wounds, or have lines, etc., that be beneficialto avoid or target for repositioning.

Image Standardization

In an aspect of the invention, techniques can be provided to permitvisual data obtained from a camera to be standardized. Suchstandardization can, in some implementations, improve documentation.Image characteristics that may need to be standardized include imageorientation, viewing angle, viewing distance, brightness, color, etc. Toassist in image standardization, a visual reference 400 may be placedwithin the field of the image 405, as shown in FIG. 4. This visualreference can take the form of a sheet, ruler, or sticker of a knownsize, shape, and color. The visual reference may include standardreference lengths, colors, and orientation indicators. The camera, orother image processing functionality provided by the system, can thenprocess the image according to the appearance of the reference such thatall images conform to the same standard.

The reference may also take the form of a light source, as shown in FIG.5. For example, one or more lasers 500 can be shone from the cameraunit, or from another source, onto the image. The laser light isdirected towards the area of interest. The laser light may have acombination of features, including known size, shape, orientation, andspread. Image standardization can help better track the currentcondition and progression of an area of skin or a wound.

In FIG. 6, laser light is focused on an area of interest (i.e. apressure ulcer). In an embodiment, the laser light has a matrixorientation as shown in FIG. 5, which is viewable by an associatedcamera 600. As the viewing distance increases, the area withinindividual squares of the matrix increases. The laser light also has oneor more known wavelengths, such that the color can be standardized. Thelaser light may, but need not, have a wavelength in the visible spectrumas long as that wavelength can be viewed by the associated camera orother imaging device.

To aid in documentation, images can be timestamped in at least someembodiments. Timestamping images will allow for the creation of atemporal record of how a wound or area of interest evolved over time fora specific patient.

In some situations, it may be necessary to take a temporal series ofpictures of a patient, or of a patient's condition. For example,pictures of a patient's pressure ulcer may be taken daily in order totrack progression of the ulcer. In order to allow for more consistentdata gathering, an overlay 610 of a prior image can be projected ontothe camera, also as shown in FIG. 6. The user can use this image overlayto help re-approximate viewing angle, distance, orientation, etc.

Indicators on Sensor

As shown in FIGS. 7A-7B, in some embodiments there may exist indicators700 on the sensor, for example LEDs, which give information about thepatient. These indicators may indicate which side the patient is on,when a patient requires a turn, which area of the body has been exposedto the most pressure, which direction a patient should be turned onto,or when a patient has been turned sufficiently to satisfy a turningprotocol or to depressurize a given area. For example an LED on the leftside may turn on when the patient is on their left side. Similarly, inanother implementation or setting, the LED may be used to indicate whena patient should be turned and in which direction a patient should beturned. The LEDs may also indicate the relative pressurization levels atdifferent body regions.

In some embodiments of these sensor indicators, the indicator may bedisplayed only when triggered. Triggering, as opposed to being onconstantly or periodically, can allow for reduced battery consumptionand reduced light pollution. In some embodiments, the caregiver mayprovide the trigger as shown at 750. The trigger may take the form ofone or more of a single tap or sequence of taps on the sensor asdiscussed hereinafter in connection with FIG. 9, exposure of the sensorto given threshold of light, a switch or button on the sensor, or awireless communication (which may include RF, sound, light) to thesensor, in response to which the indicator LEDs indicate, for example,which sides should be avoided as shown at 755, allowing the caregiver tomake clinical judgments at 760. In one implementation of the lightthreshold trigger, the threshold of light would be exceeded when thecaregiver lifts the sheets or clothing to view the sensor, and the LEDswould then come on. The wireless communication can be provided by thecaregiver, either by sound or wireless communication generation. In oneimplementation of the wireless communication, the caregiver can carry anRF transmitter that transmits a signal to the sensor when the caregiveris near or when the caregiver presses a button on his/her transmitter.The transmitted signal causes the indicators on the sensor to display.

Patient Self Roll

Patients can often reposition themselves to some degree. As shown inFIGS. 8A-8B, in an aspect of the invention the system may be used toencourage repositioning and/or to encourage a somewhat specificdirection of repositioning, as shown at 800. For instance, if it isdesired to have the patient reposition onto their left side, 805,encouragement may be given for the patient to roll onto the left side asshown at 810. Such encouragement can include:

Audio guidance, which may include voice guidance, the voice of a knownperson (patient himself/herself, loved one, caregiver, famous person,song, music), or a generated voice

Visual guidance, lights, lights of increasing brightness, lights ofvarying color or brightness, blinking lights

Noises, beepers, sirens

Physical guidance, including a push, nudge, elevation or angle change ofthe support surface, a pressure change of the support surface,vibration, tickle, such as via a feather, etc.

Temperature

One or more of these methods can be used in combination eithersimultaneously or in spatial or temporal relation to one another.Certain stimuli may encourage the patient to turn away or towardswithout waking up or greatly disturbing sleep. The light or audio orphysical stimuli are examples. Patients may naturally turn away fromsound, lights, or nudges. In this way a patient may be encouraged toreposition according to a protocol or avoid pressure on certain areas. Apatient self-turn reduces the need for caregiver interaction andpromotes patient independence. If a patient does not repositionsufficiently, determined at 815, a caregiver can be notified as shown at820. In an embodiment, the stimuli for turning can be external to thepatient sensors, such as a unit on the bed, as shown at 850 in FIG. 8B.

Caregiver Units

In an aspect of the invention, the caregiver can also carry componentsof the system with them. In one implementation, the caregiver has abadge, nametag, bracelet, or other wearable device which is recognizedby the system of the present invention. The caregiver is associated withone or more wearable devices, which each comprises an identifier (suchas a name, number, code, etc.). The wearable device wirelessly transmitsto base stations that are in known locations. As can be appreciated fromFIG. 9, discussed hereinafter, using the methods previously described inthe section on “Location Sensing”, the system can determine when thecaregiver is in a given room, provide information about when thecaregiver is interacting with a patient or other caregiver, or candetermine when the caregiver is in any particular location, such as aroom, the nursing station, supply closet, or hand-washing area. Thelocation of the caregiver or indication of caregiver-patient interactioncan be used to determine when a caregiver helps to reposition a patient.This can be used to determine who is repositioning a patient and todetermine if sufficient self turns by the patient are being performed.Caregiver devices can also be used to login to the system when enteringinformation or to help pull up or assign patient information or datarelated to the patient(s) that the caregiver is assigned to. Devices canbe wirelessly charged, passive RFID based, or charged by a physicalconnection. In one implementation, the devices can be chargedinductively by having the device placed in close proximity to a chargingunit, such as a charging surface or box. The wearable device can alsodisplay or present information visually or audibly. The unit may alsoindicate when alarms/notices are given. For instance a nurse may begiven an audible message or a written message to indicate that a givenpatient requires turning, or has exited bed, or has fallen. Lights, suchas LEDs, may give information, including alarms as well.

The caregiver can also carry a device, such as a handheld reader orscanner. This reader can be used to scan or wirelessly communicate withone or more of patient sensors, a bed or room sensor, a patient IDtag/bracelet, etc. In an embodiment, the device can communicate with acomputer or with a sensor or node network or other wirelesscommunication network. In some embodiments, the device can include abarcode reader. In various embodiments, the device can be handheld,attached to a computer, a phone, or a bracelet. The device can also havean audible or visual information display as described above for thewearable device. These devices and the wearable devices can also be usedfor communication between patients and caregivers or between caregiverthemselves, again as illustrated in FIG. 9, discussed below.

Alternating Pressure Mattress Detection

Acceleration and orientation monitoring of the patient may be used tomonitor for motion caused by an alternating pressure mattress. Themonitoring system of the present invention, by detecting patientaccelerations, can determine if a patient is being repositionedsufficiently. Threshold acceleration values can be set, such that if theacceleration threshold is not met in a specified period of time, then itcan be assumed that the patient is not being repositioned sufficiently.Alternating pressure mattresses utilize a series of inflatable air cellsthat inflate in a regular pattern, so as to encourage tissuedepressurization of the subject lying on said alternating pressuremattress. This pattern of inflating/deflating air cells will generallycause rhythmic accelerations in a patient lying on the support surface.If no rhythmic accelerations are detected that are consistent with theknown pattern of the support surface, then it can be assumed that thealternating pressure mattress is not turned on or is not functioningproperly. Specialty support surface actions, which include alternatingpressure or repositioning, may cause characteristic accelerations on thebody of the patient. For instance, many support surfaces that providealternating pressure or repositioning do so by inflating or deflatingair cells within the support surface. This inflation and deflation isoften associated with small vibrations form one or more components ofthe support surface system, such as a pump or compressor.

Caregiver Interaction with Sensor

In some embodiments, the caregiver can communicate with the monitoringsystem of the present invention by physically interacting with thepatient associated communicator, such as, for example, by tapping asshown at 900 in FIG. 9. In such embodiments, the accelerometer andsoftware on the sensor can be configured to monitor for taps to the PAC,shown at 905-940. In such a manner, a caregiver can tap the PAC tocommunicate with the system. This communication method can be used tocommunicate that a caregiver provided a repositioning procedure or thatthe caregiver is interacting with the patient. A caregiver may also usetaps to indicate his or her presence so that the patient sensor cancommunicate with her via a display, such as one or more LEDs, beeps, ora display screen. The tapping motion causes accelerations/decelerationsthat can be detected by the PACs onboard accelerometer. The system canbe configured to recognize specific patterns ofaccelerations/decelerations in order to communicate information with thesystem. The magnitude of acceleration/decelerations that are consideredto be consistent with a “tap” can be predefined in the system.Furthermore, different patterns of successive taps can be used tocommunicate different information, as at 935. As such, the PACsaccelerometer functions as an input device for caregivers. For example,if a caregiver wants to inform the system that they are physicallypresent with the patient, they may tap the PAC in a specified pattern,such as two taps at ˜1 Hz. As another example, if the caregiver wants toactivate the PACs onboard LEDs (which can visually display data such ascumulative pressurization time on each side of the body), they can tapthe PAC three times at ˜1 Hz. Those skilled in the art will recognizethat there are various methods of communicating with the monitoringsystem via the PACs onboard accelerometer and associated processingalgorithms.

Sleep Monitoring

The system can monitor for characteristic movements associated withdifferent indicators of sleep quality. These characteristics includeapnea and movement, activity, or orientation during sleep. Reports canthen be given about sleep quality to patients and caregivers.

Feedback to Support Surface

In some embodiments, the system can include a pressure measurementsystem which can produce a pressure map of reasonable precision thatthen feeds back to a support surface. This pressure sensor system,feedback, and support surface can be a standalone system or it caninteract with a sensor network. Knowing where pressure is higher thandesired allows for a support surface to automatically respond byoptimizing the pressure experienced by a patient. If the support surfaceis unable, by its automatic response means, to correct for the undesiredpressure, it can alert a caregiver to decide about providing furthercare. The data can be used to inform treatment and parameters for care.

Monitoring Mobility/Activity to Determine Need for DVT Prophylaxis

Patients who are immobilized for long periods of time often requireprophylaxis to prevent against deep venous thrombosis (DVT). A DVT is ablood clot that forms in a vein (typically in the leg veins) and oftenis a consequence of venous stasis, which can occur from prolongedimmobility. Patients considered at risk for DVTs will generally receiveDVT prophylaxis, which can be pharmacologic or mechanical in nature.Pharmacologic DVT prophylaxis consists of systemic anticoagulation (i.e.heparin, enoxaparin) which is delivered to patients via subcutaneousinjections. Mechanical DVT prophylaxis consists of sequentialcompression devices (SCDs) which are pneumatic compression stockingsthat are affixed to the legs of patients and then inflate/deflate inorder to promote blood flow and thereby prevent venous stasis. Asmentioned previously, a major risk factor for DVTs is prolongedimmobility. In an aspect of the invention illustrated in FIG. 10, themonitoring system of the present invention is designed to monitor apatient's movements and activity level, and the system can use thisinformation to generate an ‘activity index’ value for a given patient,shown at steps 1000-1075. The activity index value, shown at 1035,incorporates factors such as: total activity time, amplitude/frequencyof movements, acceleration, sustained inactivity time (i.e. how long arethe intervals between activity), etc.

Based on the “activity index” score for a particular patient, physicianscan decide whether or not DVT prophylaxis is indicated for a particularpatient.

To improve the tool, the following factors are incorporated into theanalysis, and can be used to generate a DVT “risk score”, shown at 1060:

-   -   1. Age, height weight, of patient    -   2. Is patient a smoker?    -   3. Does patient have CHF?    -   4. Is patient on hormonal contraception?    -   5. Malignancy present?    -   6. Previous DVT or PE?

Note that weighting for all of the variables can be customized byindividual physicians, care providers or institutions, such that theycan increase/decrease the threshold for DVT prophylaxis. A set ofdefault values can be initially provided. The system is designed to helpphysicians objectively decide what treatment is best for their patients.Currently, physicians have limited objective information to understandhow well a patient is ambulating.

Wireless Communication

In certain cases, wireless communication via a device with an antennacan be affected by the surface upon which the antenna lies. Forinstance, a device on the surface of the skin can have its antennaperformance affected by the electromagnetic and dielectric properties ofthe body. To shield the device from such effects caused by the body, insome embodiments the device may have material between the body and theantenna that shields or reduces the relative effect of the body on theantenna performance. For instance, a material with a high dielectricconstant can be placed on the device between the antenna and the body toserve this purpose.

Automatic Decompression Threshold Calculation

In an embodiment, the system can automatically calculate at least onesuggested decompression threshold/interval. The decompressionthreshold/interval refers to the minimum amount of time that an area ofthe body needs to experience reduced pressure or no pressure in order toadequately re-profuse that area of the body, thereby preventing ischemiaand tissue damage. Once an area of the body has surpassed the suggesteddecompression threshold/interval, that area of the body can once againbe pressurized with lower risk for causing tissue damage. Thedecompression threshold/interval can be calculated by taking intoaccount factors selected from a group comprising: patientcharacteristics (i.e. Braden score, age, co-morbidities,size/weight/BMI/body mass distribution, etc.), patient variables(mobility, activity, moisture, nutrition level, experienced or estimatedsheer force, medical conditions, vital signs, health conditions, healthstatus, previous skin conditions, and medications, etc.), environmentalfactors (type of bed surface, ambient temperature, humidity, etc.). Oneor more calculation schemes can be used by the system and selected bythe user.

The system can also allow for a decompression threshold that is variablefor any given patient. One common usage is to have a decompressionthreshold for an area of the body vary with the amount of time the areaof the body has experienced pressure. For instance, the decompressionthreshold can take the form of:D0+D1*[duration of pressure]

where D0 and D1 are constants that can be set or varied or varyautomatically based on data about the patient or facility.

The system, methods, and devices of the present invention provide animproved method for both calculating the appropriate decompressionthreshold/interval for a region of the body and also monitoring saidregion to determine when adequate decompression time has been achieved.

Variables that may affect calculated decompression threshold, includevitals (such as pulse ox, heart rate, breathing rate, blood pressure),time on a given side, duration of pressure orientation, existence ofother wounds, patient characteristics (i.e. Braden score, age,co-morbidities, size/weight/BMI/body mass distribution, etc.), patientvariables (mobility, activity, moisture, nutrition level, experienced orestimated sheer force, medical conditions, health conditions, healthstatus, previous skin conditions, and medications, etc.), andenvironmental factors (type of bed surface, ambient temperature,humidity, treatment and prevention techniques used etc.). The system canalso accommodate for the ability of different parts of the body maydepressurize differently and at different rates.

Indicia on Part Associated with Sensor

An indicia may be associated with a patient sensor so that a user caneasily orient the sensor with respect to the patient. The indicia may bea visual indicator, physical feature or shape, or asymmetry. Thisindicia may be location on the sensor itself, typically the housing orenclosure of the sensor. It can also be located not on the sensoritself, but on something that is in a specific orientation relative tothe sensor at some time. One example is a label, stick, adhesive, orelement of packaging that can have one or more indicia. These elementsmay then be separated from the sensor with the user still knowing theorientation of the sensor. Another method is to have a device that candetermine the orientation of the sensor, either by mechanical, RF,magnetic, visual, or other communication means.

Flatline Detector

The system can also detect very low to no movement or situations in apatient. Such a situation occurs when the patient's breathing,heartbeat, and other physical motions have stopped. In such a case, thesystem can very quickly detect such an condition in the patient suchthat it can note the status and send an alert quickly. In certain casesit would be able to detect the situation in less than a few seconds orin less than one second and alert those who can provide help, possiblywithin enough time to help the patient. Detection can be much quickerthan for systems that detect patient motions suggestive of an abnormalstate such as arrhythmias and decompensation. In certain cases there maybe ambient movement detected by the system that are not caused by thepatient. These movements may easily be disregarded if they fall belowthe threshold for movements caused by heartbeat or breathing.Alternatively the system may learn what movements are characteristicthat don't arise from the patient. Alternatively the system may utilizea separate sensor not on the patient to determine what movements are notarising from the patient and subtract those. Alternatively, the systemmay use sensors on more than one patient or more than one sensor on athe same patient to subtract out the movements that are common, whichmay be subtracted as those movements arising from outside of thepatient. Electrical signal detection from the patient can be usedsimilarly and where movement is described above, electrical signals arereplaced in another implementation of the system. Electrical signals andmovement detection can be combined as well to further increase theaccuracy and robustness of the detection.

Having fully described a preferred embodiment of the invention, andnumerous aspects thereof, as well as various alternatives, those skilledin the art will recognize, given the teachings herein, that numerousalternatives and equivalents exist which do not depart from theinvention. It is therefore intended that the invention not be limited bythe foregoing description, but only by the appended claims.

We claim:
 1. A system for monitoring a location and orientation of apatient, the system comprising: a patient-associated communicationdevice configured to transmit wireless signals and having a definedorientation with respect to the patient, and a data analysis systemcomprising: at least one reference communication device, each located ata known location and configured to receive wireless signals transmittedby the patient-associated communication device, and a processing unitconfigured to determine a location of the patient-associatedcommunication device based at least on the wireless signals received bythe at least one reference communication device, and wherein thepatient-associated communication device comprises a plurality of LEDsthat indicate information regarding the patient's orientation during atleast one period prior to a current time.
 2. The system of claim 1,further comprising an image capture device for monitoring a condition ofan area of the patient's skin.
 3. The system of claim 1, wherein thepatient-associated communication device is affixed to the patient. 4.The system of claim 1, wherein the patient-associated communicationdevice is affixed to a bed associated with the patient.
 5. The system ofclaim 1, wherein the patient-associated communication device is affixedto a surface proximate to a bed associated with the patient.
 6. Thesystem of claim 1, further comprising at least one stimuli generator forencouraging a patient to change to a different orientation.
 7. Thesystem of claim 6, wherein the at least one stimuli generator generatesat least one signal from a group comprising audio, visual, or tactilestimulus.
 8. The system of claim 2, further comprising an illuminationdevice configured to illuminate an area of interest of the patient'sskin.
 9. The system of claim 8, further comprising a visual referencetool configured to evaluate the area of the patient's skin illuminatedby the illumination device.
 10. The system of claim 1, wherein thepatient-associated communication device comprises a user interfaceconfigured to receive user input by at least one of a tap, a visualsignal, an audio signal, or an RF signal.
 11. The system of claim 10,wherein the patient-associated communication device is configured toenable or disable user input by an operator based on a proximity of theoperator to the patient-associated communication device.
 12. The systemof claim 1, further comprising computer instructions executable to assesan activity and mobility of the patient and compare the assessment toone or more risk factors to determine a risk of deep vein thrombosis.13. The system of claim 1, wherein: the patient-associated communicationdevice is configured to be positioned on the patient in a knownorientation, and the system comprises computer instructions executableto: detect, at a plurality of environmental resource communicationdevices, signals from the patient-associated communication device, andidentify, based on the known orientation of the patient-associatedcommunication device together with the detected signals at the pluralityof environmental resource communication devices, the location andorientation of the patient within a monitored space.
 14. The system ofclaim 1, wherein the patient-associated communication device isconfigured to control the one or more of the plurality of LEDs as afunction of an amount of time that the patient has spent in at least oneparticular orientation.
 15. The system of claim 14, wherein thepatient-associated communication device is configured to control the oneor more of the plurality of LEDs as a function of a cumulative amount oftime that the patient has spent in at least one particular orientation.16. The system of claim 1, wherein the patient-associated communicationdevice is configured to indicate, via one or more of the plurality ofLEDs, a current orientation of the patent.
 17. The system of claim 1,wherein the patient-associated communication device is configured toindicate, via one or more of the plurality of LEDs, compliance ornon-compliance with a predefined turning protocol for the patient. 18.The system of claim 1, wherein the patient-associated communicationdevice is configured to indicate, via one or more of the plurality ofLEDs, when a change in the patient's orientation is specified accordingto a predefined turning protocol for the patient.
 19. The system ofclaim 1, wherein the patient-associated communication device isconfigured to indicate, via one or more of the plurality of LEDs, aspecified change in the current orientation of the patient, as definedby a predefined turning protocol for the patient.
 20. The system ofclaim 1, wherein: the system comprises a plurality of referencecommunication devices; and determining the location of thepatient-associated communication device based at least on the receivedwireless signals from the patient-associated communication devicecomprises determining one or more reference communication devicesproximate to the patient-associated communication device.
 21. The systemof claim 1, wherein: the system comprises a plurality of referencecommunication devices; each reference communication device may or maynot receive wireless signals transmitted by the patient-associatedcommunication device based at least on a data communication path betweenthe patient-associated communication device and the respective referencecommunication device; and determining the location of thepatient-associated communication device based at least on the receivedwireless signals from the patient-associated communication devicecomprises determining that the patient-associated communication deviceis proximate to one or more particular reference communication devicesbased on Whether each respective reference communication device receiveswireless signals transmitted by the patient-associated communicationdevice.
 22. A method for monitoring a user, the method comprising:transmitting wireless signals by a user-associated communication devicehaving a defined orientation with respect to the user; receiving, by atleast one reference communication device located at at least one knownlocation, the wireless signals transmitted by the user-associatedcommunication device; determining, by a processor, a location of theuser-associated communication device based at least on the wirelesssignals received by the at least one reference communication device; anddisplaying, via one or more LEDs of the user-associated communicationdevice, information indicating the user's orientation during at leastone period prior to a current time.
 23. The method of claim 22, whereindisplaying, via one or more LEDs of the user-associated communicationdevice, information indicating the user's orientation during at leastone period prior to a current time comprises controlling the one or moreLEDs based on a monitored amount of time that the user has spent in atleast one particular orientation.
 24. The method of claim 22, whereinthe user-associated communication device is configured to indicate, viathe one or more LEDs, compliance or non-compliance with a predefinedturning protocol for the user.
 25. The method of claim 22, wherein theuser-associated communication device is configured to indicate, via theone or more LEDs, when a change in the user's orientation is specifiedaccording to a predefined turning protocol for the user.
 26. A systemfor monitoring a user, the system comprising: a user-worn sensor deviceconfigured to be directly or indirectly secured to the user or to anarticle worn by the user, the user-worn sensor device comprising: atleast one sensor configured to collect sensor data indicating a physicalorientation of the user; a wireless communication unit configured totransmit wireless signals corresponding with the sensor data collectedby the at least one sensor; and a display unit including at least oneLED or other visual indicator; and a data analysis system comprising: atleast one communication device configured to directly or indirectlyreceive wireless signals from the user-worn sensor device; and aprocessor configured to analyze the wireless signals to determine atleast one of a location or an orientation of the user-worn sensordevice; and wherein the display unit of the user-worn sensor device isconfigured to indicate information regarding an orientation of the userduring at least one period prior to a current time.
 27. The system ofclaim 26, wherein indicating, by the display unit, information regardingan orientation of the user during at least one period prior to a currenttime comprises displaying information indicating an amount of time thatthe user has spent in at least one particular orientation.
 28. Thesystem of claim 26, wherein the display unit of the user-associatedcommunication device is configured to indicate compliance ornon-compliance with a predefined turning protocol for the user.
 29. Thesystem of claim 26, wherein the display unit of the user-associatedcommunication device is configured to indicate when a change in theuser's orientation is specified according to a predefined turningprotocol for the user.